1. Field of the Invention
The present invention relates to an anti-lock braking system that performs without a differential speed sensor (DSS) to calculate rear wheel vehicle speed, instead relying upon information from the output shaft speed (OSS) sensor.
2. Discussion of Related Art
Rear wheel speed sensors have historically been a significant source of anti-lock braking system (ABS) warranty, because of their operation in harsh operating environments, namely, exposure to high heat and accelerations of the sensor and wire harness on the axle and placement in high splash zones. Further, they become problematic because of damage from aftermarket body builders. In contrast, there is no mechanism for the ABS to be the cause of Powertrain Control Module (PCM) or OSS sensor failures. The only connection is via a high-speed controller area network (HSCAN) bus, which may be a conventional mini-network to exchange data between computers at a high transmission rate. Indeed, OSS-based ABS diagnostic algorithms are more tolerant of some intermittent failures than conventional 3-sensor ABS.
The inventors were trying to improve reliability of the DSS and reduce the cost of an ABS system. During the investigation, the inventors determined that the DSS is actually a redundant sensor to the OSS.
It is desired to provide an anti-lock braking system that calculates rear wheel speed of a motor vehicle without relying upon any information from the DSS to do so.